1. Field
The present disclosure relates to the field of spectrometers, and more specifically to Sagnac interference spectrometers.
2. Description of the Related Art
In a Sagnac interferometer, an input light is split into two counter-circulating beams. The two beams, commonly called clockwise and counterclockwise beams, can have slight propagation variations due to some external influence. When the two beams combine again, such variations can be manifested in effects such as interference patterns.
Typically, splitting of the input light and combination of the two beams are achieved by a beamsplitter. The effect of the combined beams can be measured by scanning across the output, e.g., interference pattern, of the combined beams.
In a Sagnac interference spectrometer, a diffraction grating is included in the optical path of the counter-propagating beams. Dispersion in the grating alters the propagation direction of the two beams, shifting one with respect to the other. The shift in the beams is manifested by a variation in the resultant interference patterns. This interference pattern can be processed to determine the spectral characteristics of the counter-propagating beams. In particular, a Fourier transform of the interference pattern yields the wavelength spectra of the beams.